its page 5 of 14 if you wish to read it yourself
MRT Performance
[*]The first is the torque delivery of the engine – many customers have mentioned that their standard car has a surging feeling under full throttle in Sport and Sport Sharp mode. The first time we put a Liberty GT on the dyno the cause was instantly apparent. It is hard to say exactly why Subaru wanted it so, but the GT’s standard engine management system holds the engine in closed loop fuel control WAY too long (refer Tuning 101 to your right for a quick explanation of Closed Loop Fuel Control if you aren’t sure what this is). An issue on its own, but when combined with the highly active ignition timing system Subaru ECU’s use, this then feeds into another problem.
In later model cars such as the Liberty GT, th engine management system runs very active ignition timing strategies. In simple terms, more ignition timing (up to a point) generates more torque from the engine. However, too much ignition timing can cause abnormal combustion (detonation, which can be engine damaging). The factory ECU uses feedback from the knock sensor to constantly revise the amount of ignition timing being run to get the most torque possible without detonation occurring. If detonation is detected, ignition timing is reduced to prevent engine damage.
Copyright MRT Performance 2008
http://www.mrtperformance.com.au/files/ ... Y07-09.pdf
